Summary of the invention
Therefore, the invention provides a kind of position detector, comprise first parts, second parts, transducer, at least one modulus signal converter and at least one digital signal processor, wherein:
First parts carry a chain that is made of magnetic material element, and these elements have a central shaft, are arranged side by side in delegation, are in contact with one another and limit relatively moving, and wherein this chain has the size of variation in the direction perpendicular to central shaft;
First and second parts can relatively move in the direction that is parallel to central shaft;
Second parts carry this transducer;
Transducer comprises transmission and sensing apparatus, dispensing device is set to produce the magnetic field by element chain, sensing apparatus comprises that at least one is arranged near the pick-up loop of element chain, and pick-up loop is set to detect during first and second parts relatively move owing to pick-up loop and the changes of magnetic field that the variation of distance produces between near the element chain edge of this pick-up loop, each pick-up loop provides a simulating signal thus, and the amplitude of this signal is the characteristic of the relative position of first and second parts;
Each modulus signal converter is set to receive the simulating signal from a corresponding pick-up loop, and is converted into digital signal;
Each digital signal processor is set to receive the digital signal from each analog to digital converter, and operationally digital signal is sampled with the predetermined sampling interval, and use the characteristic variations of signal amplitude with the first and second parts relative positions, determine that first parts are with respect to second position component.
Preferably, this chain changes with repetitive mode along chain perpendicular to the size of central shaft.
Digital signal processor also can be sampled to signal with the predetermined space of rule.
Digital signal processor can be set to from the signal amplitude of first group of pick-up loop with the variation characteristic of signal position with compare from the signal amplitude of second group of pick-up loop variation characteristic with the signal position, and the adjusting range feature is to produce the signal with substantially the same amplitude characteristic from first and second groups of coils.
Preferably, dispensing device is set to produce one and is periodically variable magnetic field in time.In the preferred embodiment, digital signal processor is set to the signal from pick-up loop be sampled approaching time dependent peak amplitude basically.Alternatively, digital signal processor can be set to monitor and adjust the sampling of signal so that its time dependent peak amplitude of approach signal basically.
In a preferred embodiment, this element chain comprises a plurality of spherical, identical basically magnetic material balls, and these balls are arranged side by side with a way of contact,
First and second parts can relatively move in the direction that is parallel to the some osculatory between the ball,
Sensing apparatus comprises at least two pick-up loops, and these two pick-up loops keep at a certain distance away near the element chain setting and along element chain.
Digital signal processor is set to comprise that by use the mathematical computations of following project determines that first parts are with respect to second position component:
The arc-tangent value of the amplitude of first digital signal of sampling from the quilt of at least one pick-up loop and the ratio of the amplitude of second digital signal of sampling from the quilt of another pick-up loop at least,
On the axle of signal fluctuation around it or under the relative amplitude and the correspondence position of signal,
With a constant, this constant is determined by a peak amplitude and the ball size with the signal of change in location.
Preferably, in the present embodiment, determine by the calibration value of setting with the peak amplitude of the signal of change in location.Alternatively, in the constant of mathematical computations, use with the peak amplitude of the signal of change in location by in a period of time, the peak amplitude with the signal of change in location being sampled to determine during use.
Advantageously, in this preferred embodiment, digital signal processor is set to the amplitude of the signal amplitude that occurs with the position on the axle of signal fluctuation around it with respective signal under this compared, and the amplitude of adjusting signal be created on this and under have substantially the same amplitude symmetric signal.
Preferably, transducer comprises:
At least one group of four pick-up loops, these pick-up loops keep at a certain distance away near the ball setting of described delegation and along described delegation ball;
Wherein digital signal processor is set to measure the imbalance in the first/three pair and the second/four pair of signal, and adjusts signal to reduce two pairs of imbalances between the signal.
Alternatively, transducer comprises:
At least one group of four pick-up loops, these coils keep at a certain distance away near the ball setting of described delegation and along described delegation ball;
Be respectively applied at least one unbalanced circuit of the first/three pair of coil and second/4th pair coil in this group coil, this unbalanced circuit is set to receive the signal from pick-up loop, and comprises a pot and a subtraction circuit that is set to receive and adjust from the simulating signal of pick-up loop;
Wherein first pick-up loop in this group coil is set to receive a low signal of signal amplitude than the 3rd pick-up loop in this group coil, the 4th pick-up loop in this group coil is set to receive a low signal of signal amplitude than second pick-up loop in this group coil
And the pot that is used for the first/three pair of pick-up loop operationally part of the amplitude by increasing by the first pick-up loop signal increases the amplitude of the first pick-up loop signal, subtraction circuit operationally deducts the amplitude of the 3rd pick-up loop signal to be provided at first signal that uses in the mathematical computations
And the pot that is used for the four/the second pair of pick-up loop operationally part of the amplitude by increasing by the 4th pick-up loop signal increases the amplitude of the 4th pick-up loop signal, and subtraction circuit operationally deducts the amplitude of the second pick-up loop signal to be provided at the secondary signal of using in the mathematical computations.
The present invention also provides a kind of method of determining first parts of above-mentioned position detector with respect to the displacement of second parts, comprise: digital signal is sampled, and use signal amplitude to determine the relative position of first and second parts with respect to the characteristic variations of the first and second parts relative positions.
Preferably, this method comprises: from the signal amplitude of first group of pick-up loop with the variation characteristic of signal position with compare from the signal amplitude of second group of pick-up loop variation characteristic with the signal position, and the adjusting range feature is to produce the signal with substantially the same amplitude characteristic from first and second groups of coils.
Comprise that at described chain in the preferred embodiment of a plurality of spherical balls, this method comprises: with predetermined space the signal from the pick-up loop of transducer is sampled,
Calculating is from the amplitude of first sampled signal of transducer and arc-tangent value from the ratio of the amplitude of second sampled signal of transducer,
Determine on the axle of signal fluctuation around it or under the relative amplitude of each sampled signal and their relevant position,
And the arc-tangent value of the amplitude by using sampled signal, carry out mathematical computations determining the relative position of first parts to second parts with respect to this relative amplitude and their position and constant,
This constant is determined by peak amplitude and a ball size with the signal of change in location.
Preferably, in the present embodiment, determine by the calibration value of setting with the peak amplitude of the signal of change in location.Alternatively, in the constant of mathematical computations, use with the peak amplitude of the signal of change in location by in a period of time, the peak amplitude with the signal of change in location being sampled to determine during use.
Advantageously, in this preferred embodiment, the signal amplitude that occurs with the position on the axle of signal fluctuation around it is compared with the amplitude of the respective signal under this, and adjust signal amplitude be created on this with under have substantially the same amplitude symmetric signal.
Be set to produce in the preferred embodiment that is periodically variable magnetic field in time at dispensing device, this method comprises: near time dependent peak amplitude the signal from pick-up loop is being sampled basically.Alternatively, can monitor and adjust the sampling of signal so that sampling near time dependent signal peak amplitude basically.
Transducer comprise with the delegation ball near and the preferred embodiment of at least one group of four pick-up loops keeping at a certain distance away along this row ball in, this method comprises: measure the imbalance in the first/the 3rd and second/four pair of signal, and reduce two pairs of imbalances between the signal.
Alternatively, by provide following element to reduce imbalance in the sampled signal for transducer:
At least one group of four pick-up loops, these coils are mutually near being provided with and keeping at a certain distance away along described delegation ball;
With at least one unbalanced circuit that is respectively applied for first/the 3rd and second/the 4th pick-up loop in this group coil, this unbalanced circuit is set to receive the signal from pick-up loop, and comprises a pot and a subtraction circuit that is set to receive and adjust from the simulating signal of pick-up loop;
And may further comprise the steps: first pick-up loop in this group coil is set receives the low signal of signal amplitude than the 3rd pick-up loop in this group coil, and the 4th pick-up loop in this group coil is set receives the low signal of signal amplitude than second pick-up loop in this group coil
Increase the amplitude of the first pick-up loop signal by a part of using the first/three pair of pot to increase the amplitude of the first pick-up loop signal, and use subtraction circuit from the first pick-up signal that increases, to deduct the amplitude of the 3rd pick-up loop signal, so that first signal that uses in the mathematical computations to be provided
And increase the amplitude of the 4th pick-up loop signal by a part of using the four/the second pair of pot to increase the amplitude of the 4th pick-up loop signal, and use subtraction circuit from the 4th pick-up signal that increases, to deduct the amplitude of the second pick-up loop signal, so that the secondary signal of using in the mathematical computations to be provided.
The present invention recognizes that the amplitude of the signal that is detected by pick-up loop depends on pick-up loop and the distance between the magnetic element chain edge of close pick-up loop.Therefore, by in the size that changes the magnetic element chain perpendicular to the direction of magnetic element central shaft, can determine the characteristic relation between the signal amplitude that relative position and pick-up loop write down between pick-up loop and the chain.Therefore, unlike the prior art, the present invention does not rely on the interpolation of telecommunications order, but determines the position by the mathematical computations of the characteristic relation between the relative position that is used for definition signal amplitude and chain and pick-up loop.Therefore, the present invention can provide the 1 μ m or the accurate resolution of decimal magnitude more.
Certainly, if use a time-varying current (for example sinusoidal current) to respond to the magnetic field by element chain, the amplitude of the signal that pick-up loop write down depends on that when extracting a sampling determines the position.Therefore, for each sampling frequency characteristic relation between a position and the signal amplitude is arranged all.
The present invention also allows position detector to carry out the conversion of one or many from signal to position information in each working cycle, and therefore resolution of the present invention is not only determined by frequency of operation.
And, can use an automated procedure to come the calibrating position detecting device, and need not the intervention of a skilled operators, and position detector can also oneself be calibrated to consider the fluctuation in the signaling during use.In addition, oneself can't carry out between the operating period calibration again and when therefore needing human the intervention, position detector of the present invention can provide corresponding indication at device.
Embodiment
Fig. 1 represents a detecting device, and it is applicable to lathe providing one to be periodically variable signal with displacement, and is the type that discloses among the GB1513567, and it still is a theme of the present invention.As shown in the figure, this device or detecting device 1 comprise scale 9 and shell 10.Scale 9 is installed to first parts 50 of lathe by (directly or indirectly) regularly, and shell 10 quilts regularly (directly or indirectly) be installed to the second parts (not shown) of lathe.The relative displacement that detecting device 1 is measured between these two parts.For example, first parts can be parts of lathe, and second parts can be processed workpiece.
In this configuration, scale 9 is formed by a nonmagnetic substance pipe 4, is provided with a plurality of magnetic balls 2 in it as the crow flies.Scale 9 is supported by scale support member 3a and 3b with the relation that is fixed to first parts 50.Ball 2 is spherical basically identical steel balls, they with scale 9 and shell 10 between the parallel straight line of the direction that relatively moves on be arranged side by side with a way of contact mutually.These balls are limited to move each other.In shell 10, provide and send coil 7 and pick-up loop 6 (see figure 2)s.
As shown in Figure 1, scale 9 is set to be assemblied in and passes in the tubular hole that shell 10 provides.Enter shell 10 for fear of the porch dirt, each end in tubular hole in the enclosure provides a seal 5.
Fig. 2 represents the transmission coil 7 in the shell 10 and the layout of pick-up loop 6.As shown in the figure, send coil 7 and a plurality of pick-up loop 6 (6a, 6b, 6c, 6d) be positioned at ball 2 around.It is coaxial mutually to send coil 7 and pick-up loop 6, and coaxial with the center line 8 of these balls.Ball 2 and coil 6 and 7 can move mutually in the direction that is parallel to line 8.
Send coil 7 comprise a plurality of transmission coiler parts 7 that are connected in series '.Coiler part 7 ' that be associated is a pick-up loop part, for example 6a1,6b1,6c1 or 6d1 with each transmission.Each pick-up loop (for example 6a) comprises a plurality of pick-up loop parts, and 6a1 for example, 6a2,6a3, these pick-up loops partly are connected in series and to be spaced from each other corresponding to the length of ball 2 diameters or the interval of spacing P.
Fig. 3 is the block scheme of the prior art electronic circuit that uses of being associated with detecting device shown in Figure 1.This circuit comprises primary processor 20, and it is a 80C31 processor typically.Primary processor 20 has its nonvolatile ram (RAM) 23, and this nonvolatile memory 23 is connected with a related battery (41), is used for powering when primary source failure.This nonvolatile memory 23 is preserved measured displacement data.Also provide program read-only memory (ROM) 22 to be used for the operation of primary processor 20.
Keypad/display processor 24 is connected in series to primary processor 20, and this keypad/display processor 24 is connected to display 25 and keyboard 26, and the input and output of supervisory keyboard and to the video data of primary processor 20.
Provide RS232 port 27 being used to be connected to the external unit such as computing machine, and this port 27 is connected in series to primary processors 20.Except display 25, also have a display 28 to be used for showing measured displacement with inch or millimeter.
The clock signal of 10.16MHz is provided to primary processor 20 from oscillator 21.Output from oscillator 21 also is output to frequency dividing circuit 29, and this frequency dividing circuit 29 offers digit counter 30 and another frequency divider 31 to the clock signal of a 5.08MHz.Frequency divider 31 the clock signal of 5.08MHz divided by 5080, a 1KHz signal being offered sine-wave generator 32 and to be respectively applied for X, Y, three signal adjustment units 33,34 of Z axle and 35 (for each axle provides a displacement detector 36,37,38).The output of sine-wave generator 32 also is imported into each signal adjustment unit 33,34 and 35.Signal adjustment unit 33,34 and 35 is directly connected to relevant detection device 36,37 and 38.
Come the signal output of self-detector 36,37 and 38 to be imported into corresponding signal adjustment unit 33,34 and 35, this signal is used to make digit counter 30 to stop.The enabling pulse of digit counter 30 is the output of frequency divider 31.The output of digit counter 30 is imported into primary processor 20.
Primary processor 20 also is equipped with power supply 39 and resetting means 40.Provide an axle selection wire 42 that primary processor 20 is connected to each signal adjustment unit 36,37 and 38, can select to carry out the axle of displacement measurement with the permission primary processor.Therefore, this configuration can be controlled vertically arranged three detecting devices mutually.
Below the simple operation of describing prior art circuits shown in Figure 3.Oscillator 21 provides a 10.16MHz clock signal, and this signal is divided down to the 5.08MHz clock signal to be input to digit counter 30.Frequency divider 31 further carries out the 1KHz reference pulse of frequency division to provide one to be used for signal adjustment unit 33,34 and 35 to this 5.08MHz signal, and as the enabling pulse of digit counter.Use this 1KHz clock signal to drive sine-wave generator 32 then.
Each signal adjustment unit 33,34 and 1KHz sinusoidal signal that is applied to corresponding transmission coil 7 of 35 outputs.Therefore, each sends coil 7 and is provided a signal, is parallel to the magnetic field of the line 8 among Fig. 2 with generation.Because the changes of magnetic field that moving to axial between ball 2 and the shell 10 causes is at each pick-up loop 6a, 6b produces respective change in the signal of responding among 6c and the 6d.
The top of Fig. 4 a is represented respectively from pick-up loop 6a, and 6b, the signal A of 6c and 6d output, B, C and D are the changes in amplitude of position of the ball of P along spacing.Fig. 4 b will be discussed in conjunction with the present invention in the back.
From Fig. 4 a as can be seen, each signal A, B, the amplitude of C and D is sinusoidal variations with displacement, and its cycle is P and corresponding to the diameter of ball 2.And around zero amplitude fluctuation, promptly they are not from zero offset for sinusoidal wave A, B, C and D.Typically, fluctuation only is 6% of skew.
Each signal A, B, 1/4th spacings of phasic difference mutually of C and D.This is because pick-up loop 6a, 6b, 6c and 6d be 1/4th sphere gap P at interval respectively.Signal processor (not shown) in each detecting device 36,37 and 38 from signal A subtraction signal C and from signal D subtraction signal B so that periodic waveform A-C and the D-B shown in Fig. 4 a bottom to be provided.These waveforms are represented the amplitude of 1KHz signal frequency.Then, this signal processor is 45 ° of the phase delay 1KHz signal of signal A-C, and the phase place of D-B signal shifted to an earlier date 45 ° of 1KHz signal.
Provided a phase modulated signal signal A-C and D-B mutually then, this is preferred for the practical application purpose.The signal of gained is a constant amplitude sinusoidal waveform, and its phase place is directly proportional with the relative displacement that causes owing to relatively moving of scale 9 and shell 10 (being first and second parts of lathe therefore).Detecting device 36,37 and 38 outputs to corresponding signal adjustment unit 33,34 and 35 to this signal.
When the phase place of determining the gained signal is a predetermined value (for example 0 °), signal adjustment unit 33,34 and 35 output axle digit pulses (axis bit phase).Using this digit pulse to make by the counter 30 from the impulse starting of frequency divider 31 then stops.Signal from frequency divider 31 is the pulse of a 1KHz, and it is the input of generator 32.Therefore, digit counter 30 provides a count value, the 1KHz reference signal that this count value and sine-wave generator produce and after the phase shift additions that form in signal adjustment unit 33,34 and 35 the gained phase difference between signals directly proportional.
Fig. 5 represents how to calculate relative displacement by primary processor 20 in the prior art.The output of digit counter 30 provides a position counting, and this counting can be represented by a zig-zag with change in displacement shown in Fig. 5 a.This counting is the value between 0 to 5079, and when ball 2 diameters were 1/2 inch or 12.7mm, this counting represent 0 displacement of arriving 12.7mm.Therefore, 0.0025mm is represented in each position.But because this counting is reset to 0 after the moving of 12.7mm, primary processor 20 must change each counting count the relative displacement (Fig. 5 b) that this is called as a spacing counting and represents 12.7mm.The displacement of each 12.7mm represents one of the spacing counting to increase progressively.Except position counting and spacing counting, also have a skew, it has provided the position with respect to selected data, and has 0 to-1 2.7 value (Fig. 5 c) in the case.Therefore, the total relative displacement between first and second parts is:
Relative displacement [mm]=(position * 0.0025)+(spacing * 12.7)+skew
Therefore, count, might use this method to come relative displacement between surveyors' staff 9 and the shell 10 by periodicity to the periodic waveform of detecting device 1.
But as previously mentioned, these devices have finite resolution, and can not calibrate automatically or self diagnosis.And these prior art position detectors produce non-standard signal, need the equipment of OEM design to come signal is decoded so that positional information to be provided.
In contrast, position detector provided by the invention can be calibrated and self diagnosis automatically, has high resolving power, and also producing can be by the industry standard signal of the device decodes that can buy.
Fig. 6 is the block scheme that is used for the circuit of signal Processing among the present invention.For simplicity's sake, expression comprises the coil block 100 that sends coil and pick-up loop in simplified form, and it constitutes not variation.Shown in circuit only be used to detect displacement along single shifting axle.
Transmission coil (not shown) in the coil block 100 is driven with 10KHz by amplifier 200.Signal A, B, C and D be with original the same, wherein, for example with earlier in respect of figures 4a describe identical, from A, deduct C to produce signal A-C, from D, deduct B with generation D-B.
Be very difficult to production line coil assembly 100 in the practice so that A and C signal complete equipilibrium are promptly, identical at the amplitude and the C signal of P/2 position a-signal.Therefore, need a unbalanced circuit as described below.Certainly, if be digital signal at first, be fed to processor 500 then to analog signal conversion, processor 500 oneself can be set to carry out signal operation as described below, and therefore replaces unbalanced circuit.
In order to solve this imbalance, assembly 100 is arranged so that physically the signal A of induction is less than signal C.Then, increase the sub-fraction kA (Fig. 6) of A at summing point 300 (Fig. 6), and A (the 1+k)-C that therefore bears results.Use a numerical control pot 400 to produce this part kA.This is to be provided with by a serial link from primary processor 500.
Similarly, at summing point 600 signal D and B are made up with the D that bears results (1+k ')-B.In the case, use numerical control pot 700 to produce this part k ' D.
These signals are amplified by amplifier 800 and 900, and by analog to digital converter 155 and 110 digitizings, are read by serial link 156 by processor 500 then.Processor 500 uses these digital values to calculate the relative position of coil block 100 with respect to ball 2.
Shown in Fig. 4 a, Utopian signal A-C is sinusoidal wave form, is defined as Msin (2 π d/P), and wherein d is the actual displacement of assembly along sphere gap P, the amplitude peak of M representation signal A-C.Similarly, the form of Utopian signal D-B is M ' cos (2 π d/P), the wherein amplitude peak of M ' representation signal D-B.The ratio of first signal and second signal in these two signals, i.e. (A-C)/(D-B) is M/M ' tan (2 π d/P).Therefore, after the value of knowing ratio M/M ', might utilize following equation, use arctan function and one preset time signal A-C and the range value of D-B, the value of the displacement d that calculates in this preset time:
Refer back to Fig. 4 a, in the position near P/4 and 3P/4, the value of D-B signal is lower, goes to zero.Therefore, ratio (A-C)/(D-B) is very high.If ratio (A-C)/(D-B) is greater than one, then usage rate (D-B)/(A-C) is more convenient.This is because the algorithm of arc tangent that is used to the value of-1 to+1 scope of calculating is simple Taylor series.
If ignore the algebraic symbol of this ratio, so its value between 0 and 1, and arc tangent 0 in+π/4 scopes.The arc tangent transformation result of solid line among Fig. 4 b representative this ratio in a sphere gap scope, i.e. the value of arctan (N/D), wherein D be (A-C) or (D-B) in the greater, N is the smaller.
By checking the symbol of signal A-C and D-B, can determine signaling zone (quadrant) 0 to P/4, P/4 to P/2, P/2 are to 3P/4, or 3P/4 is to P.For example, shown in Fig. 4 a, signal A-C and D-B are positive at signaling zone 0 to P/4, are that positive, D-B bears at signaling zone P/4 to P/2 A-C.Therefore, can distinguish each signaling zone.
And, by checking the relative amplitude of signal A-C and D-B, might determine pick-up loop 6 is positioned at which half part of each signaling zone.For example, shown in Fig. 4 a, in signaling zone 0 the first half parts to P/4, the amplitude of D-B is greater than A-C, and is opposite in the second half parts of signaling zone 0 to P/4.
This information is made up to provide a unique value that is used for coil block 100 (being second parts therefore) in the position of any one sphere gap with arc-tangent value.This is illustrated by the broken lines in Fig. 4 b.
For a 10kHz system,, signal A-C and D-B are carried out single sample at least in every circulation with the speed (and in the 10kHz of prior art system, carrying out 1000 sampling of per second) of 10,000 sampling of per second.Although almost can sample by any point (except zero crossing) in circulation, be that the peak value (plus or minus) in each circulation is sampled to obtain peak signal ideally.Certainly, only when carrying out the sampling of signal A-C and D-B simultaneously, above-mentioned conversion method is only effectively.
After each sampling, carry out above-mentioned conversion to provide a position in the sphere gap.This position and previous position are compared with definite amount of movement, and before carrying out next one sampling, export this change in location.The incremental variations that measured is in the position.Different with prior-art devices, be not equal to the variable that spacing is counted, although can introduce native system to off-set value yet.
In order to make measured position incremental variations is correct, supposes that the maximum between the described conversion moves less than P/2.This hypothesis makes might be determined amount of movement and need not to have the variable that is equal to the spacing counting.For example, if position detector from first sample note the position be 7P/8 (seeing Fig. 4 b), then from second sample note the position be P/8, being no more than the sole mode that this variation takes place under the situation of P/2 at amount of movement so is that position detector moves to another adjacent ball, and does not return along this same ball.In most of actual conditions, this hypothesis is complete acceptable.
The slew rate limit of signal the maximal rate or the resolution of position detector work.In the prior art, switching rate is fully by frequency of operation decision, normally every millisecond once (every circulation primary).For a 12.7mm spacing position detector, available maximum possible machine speed is 6.35m/s (being determined by (P/2) * frequency).Switch technology of the present invention is not exclusively by frequency of operation decision, can be every circulation many times, therefore be suitable for the machine of speed up to 63.5m/s.But actual maximal rate may be subjected to the restriction of data transmission rate.
The calibration of system of the present invention (the promptly feasible site error minimum that is caused by imperfectization signal) can be finished by the combination of following process.At first, the sample point in one (10kHz) circulation is set to consistent with the peak value in the waveform.Secondly, measure the imbalance of A in, and use aforesaid digital potentiometer 400 and 700 to reduce this imbalance to C and D to the B signal.The 3rd, poor among the amplitude peak M of measuring-signal A-C and D-B and the M ', and to correction factor of described transformation applications.At last, the position of being calculated according to a known standard displacement inspection.
Might carry out first three process and not standard displacement of reference.If sample point not at peak point, can be reorientated sample point.Digital potentiometer is set to produce symmetrical A-C and D-B signal, and promptly positive and negative peaked amplitude is identical.M and M ' level are the peak value measurement values of A-C and D-B signal.If system is designed to monitor continuously these signal levels, might carry out correction continuously so, although must consideration do the required time like this.The purpose of this correction is calibration (being error correction) state when returning to original calibrated.By this method, can greatly reduce because the influence of the skew that temperature, time service frequency or other factors cause.
Can be the error that measures: a) storage and use the position of being calculated continuously, or b to proofread and correct) can determine that a mathematic(al) representation is similar to and correction error.
With reference to the block scheme of figure 6, the program of processor 500 is stored in the nonvolatile memory 120.Calibration data also is stored in this storer.This storer is an electric erasable, Reprogrammable, ROM (read-only memory) (EEPROM).
From processor 500 position data is outputed to line driver 130.The form of this output data is the A of phase phasic difference 90 degree normally, the B pulse.This is 2 Gray codes of industrial standard that are used to transmit the incremental positions data.Each of the state of output line changes the change in location represent a resolution unit, 1 μ m for example, 2 μ m, 5 μ m, or 10 μ m.Direction is determined by the order that circuit changes.Can certainly use other data layout.
Can be input to processor 500 to data by line receiver unit 140.During calibration process, and, need this input for download processor program and out of Memory (for example resolution).These data are sent to storer 120 and store.Because line driver 130 and receiver 140 are shared common line, they are never worked simultaneously.150 controls of Boot loader logical block are input or output data.When powering up to transducer at first, incoming line of Boot loader logical block 150 inquiries is to determine whether to have connected a programming/calibrating installation (for example computing machine).If receiver 140 is enabled, and data download.If do not detect programming/calibrating installation, then load and run memory 120 in program, i.e. normal running.
Power supply 160, power-on reset circuit 170 and clock generator 180 are supported the operation of other circuit.
Processor 500 also produces describes the numerical data with sine wave of coil drive frequency 10kHz.This data serial is sent to digital to analog converter 190, and this digital to analog converter 190 offers coil drive amplifier 200 to this input signal then.
Under the situation that does not depart from the scope of the invention, can make amendment to the present invention.For example, the magnetic ball chain in the scale 9 can replace with the magnetic packing ring of a plurality of different-diameters that are arranged in order.These packing rings can have different thickness, and have edge flat or that tilt at the most close pick-up loop place.But the advantage of ball is to be easy to process with high dimensional tolerence, and is therefore cheap.
In a word, the invention provides a kind of position detector, its resolution not exclusively by the frequency of operation decision, therefore can provide positional information many times a working cycle.And, the invention provides a kind of position detector that can use the automated procedure calibration, need not the intervention of skilled operators.In addition, this position detector can oneself be adjusted with the signal fluctuation in consider using, and when device oneself can't be carried out the calibration again in the use and therefore need human the intervention, can also provide corresponding indication.And this position detector produces industry standard signal, and the equipment that does not rely on the OEM design is decoded so that positional information to be provided to it.